Incased electrical apparatus



u 1 E. D. TRE NoR -S I ENCASED ELECTRICAL APPARATUS Filed Ma rch 4, 1930 1 I P I I IHHH 3\ ll bfr Patented June 2, 1931 UNITED STATES PATENT OFFICE EDWARD D. TREANOR, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK INCASED ELECTRICAL APPARATUS Application filed. March 4,

My invention relates to encased electrical apparatus such as transformers and its general object is to provide an improved arrangement of leads for conducting a heavy current through the casing between the apparatus and the outside circuit or terminals to which the leads are connected and supply the current. Transformer casings are usually made of magnetic material such as sheet steel. A conduetor or lead connected to the apparatus and carrying current through an opening in the casing will be surrounded by a magnetic field. If the current is of large value, it has been found that the magnetic field may extend into the adjacent magnetic material of the casing around the opening and produce so much heat as to cause objectionably high temperatures. The invention provides an arrangement which avoids this objectionable result.

Further objects and advantages will appear from the following description taken in connection with the accompanying drawings in which Fig. 1 is a view, partly in section, of an encased transformer with the conductors from its low voltage winding arranged in accordance with the invention and Fig. 2 is a detail sectional View of the conductors where they pass through the casing of the transformer.

Like reference characters indicate similar parts in both figures of the drawings.

The invention will be explained in connection with the encased transformer shown in Fig. 1 but it will be obvious that its application is not limited to this particular form of electrical apparatus.

The transformer 10 shown in Fig. 1 is immersed in a body of insulating oil 11 in a casing 12 of sheet steel. The transformer 10 has a high voltage winding connected by leads 13 to outside terminals 1 1, the leads 13 being insulated from the casing 12 by insulating bushings 15. The transformer also has a low voltage winding connected through leads 16 to outside terminals 17. The leads 16 are respectively connected to their outside terminals 17 by conductive members 18 and 19 extending through an opening in the casing 12. The member 19 is of short tubular or 1930. Serial No. 433,168.

ring shaped form and is fitted into an opening in the cover of the casing 12 so that it is in contact with the casing structure and thus conductively connected to it. The member 18 extends axially through the opening in the member 19 and the two members 18 and 19 are separated and insulated from each other by a bushing 20. The member 19 is provided at one side with one of the outside terminals 17 and at the opposite side with 1" an inside terminal 21, one of the leads 16 from tne low voltage winding being connected to this inside terminal 21. The other lead 16 from the low voltage winding is connected to the inner end of the member 18. The two outside terminals 17 are connected to the conductors 22 of an outside circuit. The member 19 and the casing 12 are connected to ground through the terminal 17 of the member 19 and this grounds one of the conductors 22 of the outside circuit.

The member 19 with its inside terminal 21 and the low voltage winding lead 16 to which it is connected form a conductor connecting one end of the low voltage winding to the grounded outside terminal 17. The member 18 and the low voltage winding lead 16 to which it is connected form a conductor connecting the other end of the low voltage winding to the ungrounded outside terminal 17. These two conductors, by reason of the arrangement of the members 18 and 19, are concentric where they pass through the easing 12. The same current, which is the current of the low voltage winding of the transformer flows in the two concentric members 18 and 19 but in opposite directions. Thus,

the tendency of the current in each of the tionable heating in the adjacent parts of the casing 12 surrounding the bushings 15. The high voltage leads 13 are therefore shown as extending through separate openings in the casing as is the usual practice.

The invention provides a simple, inexpensive and effective arrangement for carrying a heavy current through the magnetic casing of electrical apparatus Without objectionable V m heating of adjacent parts of the casing.

While a particulararrangement and a particular application of the invention have 7 been described for the purpose of explaining it, it Will be obvious that various changes 15 may be made Without departing from the spirit of the invention or the scope of the appended claims.

hat I claim as new and desire to secure by Letters Patent of the United States is: 1. Electrical apparatus enclosed in a casing of magnetic material, and conductors connected to said apparatus and extending concentrically through an opening in the easing, the outer of said concentric conductors 5 being conductively connected to said casing and to ground.

.2. Electrical apparatus enclosed in a casing of magnetic material, a pair of outside terminals, and a pair of conductors extending from said apparatus through an opening in said casing to said, terminals, one of said conductors being in contact With the casing structure and connected to ground.

3. Electrical apparatus enclosed in a casing of magnetic'material, a pair of conduc tors extending concentrically through an opening in said casing from'the apparatus, the outer conductor being in contact with the I casing structure and connected to ground. 40 i 4. Electrical apparatus enclosed in a casing of magnetic material, said casing having an opening, a conductive ring in said opening and conductively connected to the casing structure, a conductive member extending through said ring'and insulated therefrom, and conductors connecting said apparatus to said conductive ring and member, said conductive ring and member being provided with terminals outside the casing. V 5. Electrical apparatus enclosed in a casing of magneticmaterial, said casing having an opening, a conductivering in said opening and conductively connected to the casing structure, said ring having an outside terminal at one side and an inside terminal at the opposite side, a conductor connecting said apparatus to said inside terminal, and a second conductor extending from said apparatus through the opening in said ring and being insulated from the ring.

In Witness'vvhereof, I have hereunto set my hand this27th day of February, 1930.

- EDWARD D. TREANOR. 

